Summary of the Prior Art
In many parts of the country, the nature of the land precludes its usage for any farming activity other than as a pasture for cows, sheep, horses and other livestock. The contour of the land may prevent tillage by conventional equipment, even though a tractor can be driven over most of the area. In many areas in Texas, for example, the soil depth is severely limited by underlying limestone formations. Scattered rocks interfere with the operation of conventional aerating and planting equipment. Weeds, cactus, mesquite, and other undesirable vegetation may cover large areas. Nevertheless, certain pasture grasses can grow and thrive in such environment if the seed can be planted in soil that has been sufficiently disturbed to be aerated.
Millions of acres in West Texas and Northern Mexico are inhabited by sparse, scattered forb and brush plants but with very little or no grass. It is not wise or practical to destroy this habitat with heavy, earth moving machinery for the purpose of planting grass seed. This is a brittle environment and wind and rain erosion of the soil could destroy the ecological balance if the heavy equipment method is used.
Also, millions of acres of improved, warm season permanent pastures, such as bermuda and kleingrass, are planted and established in the United States. Where rainfall is sufficient, many operators desire to overseed these perennial pastures in the fall with annual winter forage seed, such as ryegrass or oats, to obtain grazing for the entire year. This is presently done by slow, expensive, inefficient methods such as pulling chisels through the grass and then overseeding. The chiseling method is energy intensive, slow and leaves the pastures very rough. Till planting drills are not used and soil aeration is not accomplished with drills. Plows and planters are another method, but plows can damage the existing grass.
Most planting equipment is designed for use on tilled ground. The most common seed deposition mechanisms employ a ground engaging, rubber tired wheel for rotating a seed dispensing shaft. In the type of untilled pasture land for which this invention is designed, such wheels are continuously bouncing up and down, thus repeatedly loosing contact with the ground, and interrupting or at least varying the flow of seed to the soil being traversed by the tractor. When aeration of such soil is attempted by discs, spring tooth or rotary fork harrows, tool breakage is intolerably high, due to the presence of scattered rocks, tree roots or limestone deposits close to the soil surface. For example, when only one spike or disc of a harrow strikes a rock, the entire weight of the planting and aerating equipment is applied to that single spike or disc, resulting in the deformation, if not the destruction thereof.